Heart Care

Protect Heart with Low Blood Pressure and Cholesterol

The tightest control of the major risk factors for heart disease seems to provide the greatest protection against cardiovascular problems, says a study reported in the Journal of the American College of Cardiology.

Dr. Stephen J. Nicholls, of the Cleveland Clinic and author of the report, believes the current guidelines for reducing risk factors such as blood pressure and LDL cholesterol might need to be tightened even further.

"It is clear that each benefit we have in terms of lowering LDL cholesterol and blood pressure is going to be important, and the lower you get those measurements, the better," says Dr. Nicholls.

Prevent Fatty Deposits in Vessels

Dr. Nicholls and his colleagues looked at data on the arteries of nearly 3,500 men enrolled in seven different trials at the Cleveland Clinic.

The arteries were examined by ultrasound probes to measure the volume of the fatty deposits in the blood vessels linings - deposits that can grow until they block blood flow, causing a heart attack or stroke.

The least amount of growth was seen in those men who had the lowest levels of LDL cholesterol, the "bad" kind that contributes to the fatty deposits, and the lowest levels of blood pressure.

"The rationale for the current analysis was the belief that you should get lower LDL cholesterol and lower blood pressure, and that the benefit is greatest in getting both low," notes Dr. Nicholls. "And, in fact, the patients who had the best results in terms of growth of the deposits were those with the lowest LDL and lowest blood pressure."

Specifically, the least growth was seen in men with blood cholesterol readings under 70 milligrams per deciliter and with a systolic blood pressure (the top number of the 120/80 reading) under 120.

The guidelines for blood pressure say that men at risk can have systolic readings as high as 140 (a reading between 120 and 140 is called "prehypertension").

With blood cholesterol, the current recommendation is for an LDL level of 100 for men at high risk of heart disease, with "consideration" being given to lowering it to 70.

"If you are at high risk, LDL should be below 70," says Dr. Nicholls. "For blood pressure, you get the greatest benefit if it is below 120."

New Studies Will Look at Details

An accompanying editorial by Drs. Jonathan Tobis and Alice Perlowski of the University of California, Los Angeles, says the results did not necessarily indicate that tighter control of cholesterol and blood pressure would be beneficial.

"You need clinical endpoints to know," says Dr. Tobis, at the UCLA's David Geffen School of Medicine. "They have positive effects on total plaque volume, but the question is whether that corresponds to clinical events such as myocardial infarction [heart attack] and stroke. I suspect that they do, but we haven't proven that yet, and these trials don't prove it."

Dr. Tobis notes that the composition of a fatty deposit might be as important as its size.

Some plaques might be less stable than other and thus more likely to rupture and block a blood vessel.

"One of the studies included in the report showed that aggressive lowering of LDL reduced the size of the deposits, but we don't know clinically if that makes a difference or not," says Dr. Tobis. "Lowering LDL enough might stabilize a plaque so that you get an adequate result."

"The true determination of the impact of our therapy depends on clinical and mortality endpoints, which can only be obtained from large-scale randomized clinical trials," the editorial notes.

Dr. Nicholls says he agrees with that assessment.

While the study indicates that lowering existing guideline levels for LDL cholesterol and high blood pressure could reduce risk considerably, "we need a lot more clinical studies showing that putting the guidelines below those levels would be beneficial," says Dr. Nicholls.

Ultrafast CT Scan and Heart Disease

A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than standard x-rays.

While much information can be obtained from a regular x-ray, a lot of detail about internal organs and other structures is not available.

In computed tomography (CT), the x-ray beam moves in a circle around the body. This allows many different views of the same organ or structure, and provides much greater detail.

A new technology, called ultrafast CT scan, is now being used to diagnose heart disease.

Ultrafast CT scans can take multiple images of the heart within the time of a single heartbeat, thus providing much more detail about the heart's function and structures, and also greatly decreasing the amount of time required for a study.

Ultrafast CT scans can detect very small amounts of calcium within the heart and the coronary arteries. The presence of this calcium is believed to indicate the early formation of lesions that may eventually block off one or more coronary arteries, causing chest pain or even a heart attack.

Thus, ultrafast CT scanning may be used by physicians as a means to diagnose early coronary artery disease in certain people, especially in individuals who have no symptoms of the disease.

Others reasons for performing an ultrafast CT include assessing the condition of the coronary arteries, assessing cardiac tissue damage after a heart attack, and assessing the patency of coronary artery bypass grafts.

Ultrafast CT is used primarily for the diagnosis of coronary artery disease, particularly in persons who have no symptoms of the disease but who have significant risk factors for the disease.

There may be other reasons for your physician to recommend an ultrafast CT.

Other related procedures that may be used to assess the heart include resting and exercise electrocardiogram (ECG or EKG), Holter monitor, signal-averaged ECG, cardiac catheterization, chest x-ray, computed tomography (CT scan) of the chest, echocardiography, electrophysiological studies, magnetic resonance imaging (MRI) of the heart, myocardial perfusion scans, and radionuclide angiography.

Always consult your physician for more information.

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